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Curtis B.
Curtis B., Technician
Category: Small Engine
Satisfied Customers: 12172
Experience:  have worked on and around most engine models for 35 yrs./Polaris ATV expert
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I have a gravely model 992056, serial no. 000437. I was

Customer Question

I have a gravely model 992056, serial no. 000437. I was mowing today when the mower began to misfire to the point of almost cutting out. I know the fuel is clean and the fuel filter is new. I get the mower serviced every spring. I replaced both spark plugs and the engine started up fine and was mowing perfectly for about 5 minutes when the misfiring returned.
Any ideas?
Randy Mangum in Helotes
Submitted: 1 month ago.
Category: Small Engine
Expert:  JON replied 1 month ago.

What color are the plugs now? What color were the old ones when removed?

Customer: replied 1 month ago.
When I took the old ones out, they we very black. When I removed the new ones , one was clean, but the other was very black like the old ones.
Expert:  JON replied 1 month ago.

While engine is running, pull each plug wire one at a time and reinstall to see if engine will stay running.

Customer: replied 1 month ago.
Engine keeps running when I disconnect each wire.
Expert:  JON replied 1 month ago.

Sounds like you have a coil not firing as much . One side hotter than the other. ( giving plugs diff colors once removed) You are could also be getting more fuel to one side than the other and causing it to burn rich causing the black plug. I would regap the coil on the side that is black to make sure it has proper coil gap and fire. If it continues to burn rich, I would replace that coil.

Let me back up..... This a single or dual coil engine? What engine is on this machine?

Customer: replied 1 month ago.
Kawasaki 15 hp
Expert:  JON replied 1 month ago.

what is the spec number of engine? Does it have 1 or 2 coils?

Customer: replied 1 month ago.
I'll get you the answer later. I'm away from the house now. Have a good evening.
Expert:  JON replied 1 month ago.

Okay, no problem.

Expert:  JON replied 1 month ago.

You have a good evening also.

Customer: replied 1 month ago.
Hi Jon Sorry for the delay, but I was in the office all day. Here is the engine info. Kawasaki FH451V 15 HP. I do not know if it has 1 or 2 coils.
Expert:  JON replied 1 month ago.

you have 2 coils on this machine. I would re-gap them both just to be safe

Customer: replied 1 month ago.
How is that done?
Expert:  JON replied 1 month ago.

remove the top engine cover to display the coils. use a business card to place between the coils and the magnets of the flywheel. I can send a video or go on you tube and search how to gap mower coil and there will be many videos as visuals help me more at times

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